Google engineers are investigating the cause of a problem that shut down the company's search engine and email services on Saturday 7 April.

Services were suspended between 11.45pm and midnight. Some users trying to access the page were redirected to a search engine called SoGoSearch, suggesting that the problem may have been at the Domain Name System (DNS) server level.

"It was not a hacking or a security issue," Google spokesman David Krane told Associated Press.

"Google's global properties were unavailable for a short period of time. We have remedied the problem and access to Google has been restored worldwide."

However, Krane indicated that the company is treating it as a DNS issue. Problems at this level would almost certainly involve someone accessing one of the main servers and reassigning Google's address to a third party.

In 2003 a sustained denial of service attack partially shut down many parts of the DNS system, and last month the National Academies Research Council warned that the system is in need of an urgent upgrade.